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Chapter 3 Sectioning. Basic Topics Advanced Topics Exercises. Sectioning: Basic Topics. Summary 3.1) Sectional Views 3.2) Types of Sections 3.2.1) Full section 3.2.2) Half section 3.2.3) Offset section. Sectioning: Advanced Topics. 3.2) Types of Sections
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Chapter 3Sectioning Basic Topics Advanced Topics Exercises
Sectioning: Basic Topics Summary 3.1) Sectional Views 3.2) Types of Sections 3.2.1) Full section 3.2.2) Half section 3.2.3) Offset section
Sectioning: Advanced Topics 3.2) Types of Sections 3.2.4) Aligned section 3.2.5) Rib and web sections 3.2.6) Broken section 3.2.7) Removed section 3.2.8) Revolved section 3.2.9) Non-sectioned parts 3.2.10) Thin sections
Sectioning: Exercises Exercise 3-1: Full section Exercise 3-2: Half section Exercise 3-3: Offset section Exercise 3-4: Aligned section
Sectioning Summary
Summary • What will we learn in Chapter 3? • How to create various types of sectional views. (Sectional views allow you to see inside an object.) • Key points • Using a sectional view can be very useful for parts that have complex interior geometry.
Sectioning 3.1) Sectional Views
Sectional Views • A sectional view or section looks inside an object. • Sections are used to clarify the interior construction of a part that can not be clearly described by hidden lines in exterior views. • By taking an imaginary cut through the object and removing a portion, the inside features may be seen more clearly.
Sectional Views • What is this? • An ugly rock?
Sectional Views • A pretty rock?
Creating a Section View • The part is cut using an imaginary cutting plane.
Creating a Section View • The unwanted portion is mentally discarded exposing the interior construction.
Section Example Sectional view label Notice how the cut material is shown. Notice how the cutting plane is indicated.
Lines Used in Section Views • Cutting Plane Line:Used to show where the object is being cut. • (Phantom line type)
Lines Used in Section Views Section Lines Shows where the part is being cut. Arrows point to the portion being kept.
Lines Used in Section Views • Section Lines:Section lines are used to indicate where the cutting plane cuts the material. • Section lines are thin lines. • Section line symbols are chosen according to the material of the object • Section lines are generally drawn at a 45 angle.
Lines Used in Section Views • Common Section Line Symbols
Lines Used in Section Views • Common Section Line Symbols More section line symbols shown in Fig. 3-4 on page 3-5
Rules of Sectioning • Rule 1: A section lined area is always completely bounded by a visible outline.
Rules of Sectioning • Rule 2: The section lines in all areas should be parallel. • Section lines shown in opposite directions indicate a different part.
Rules of Sectioning • Rule 3:All the visible edges behind the cutting plane should be shown.
Rules of Sectioning • Rule 4: Hidden features should be omitted in all areas of a section view. • Exceptions include threads and broken out sections.
Sectioning 3.2) Types of Sections
Types of Sections • The type of section used depends on the situation and what information needs to be conveyed. • Types of sections • Full Section • Half Section • Offset Section • etc …
Full Section • To create a full section, the cutting plane passes fully through the object. • Used in many cases to avoid having to dimension hidden lines.
Exercise 3-1 Full Section
Exercise 3-1 • Given the top and right side views, sketch the front view as a full section. • The material used is steel.
Section lines are bounded by visible lines Visible features behind the cutting plane are shown.
Half Section • A half section exposes the interior of one half of an object while retaining the exterior of the other half.
Half Section • Half sections are used mainly for symmetric objects or assembly drawings.
Half Section • A centerline is used to separate the two halves. • Hidden lines should not be shown on either half.
Exercise 3-2 Half Section
Exercise 3-2 • Given the front and right side views, sketch the top view as a full section and create a half sectioned front view. • The material is brass.
Fill in the visible lines in the right side half section view.
Fill in the section lines in the right side half section view.
Center line divides the halves No hidden lines
Offset Section • An offset section is produced by bending the cutting plane to show features that don’t lie in the same plane.
Exercise 3-3 Offset Section
Exercise 3-3 • Given the front and top views, sketch the three missing section views in their appropriate places. The material is cast iron.